It was scary enough that a team of experts on sea-level rise projected that Maryland’s coastal waters could rise to six feet in this century. But to hammer home the findings of a new report, they included a link to a Web tool that allows readers to make like a god, sliding a scale over pictures of state landmarks until a creeping tide washes them away.

Maryland, with 3,100 miles of tidal shore along the Atlantic Ocean and Chesapeake Bay, is one of several states, including Virginia, Delaware, Louisiana and Florida, most vulnerable to sea-level rise pushed in part by global warming that has caused glaciers to melt and oceans to expand.

Coastal sea-level rise for Maryland will range from slightly less than a foot to more than two feet by mid-century, and from two to six feet by the end of the century, depending on numerous factors, including glacial ice melt, according to the projections in a recent report from the Maryland Commission on Climate Change.

As waters inch up at a pace of nearly four millimeters per year, coastal Maryland will be highly vulnerable to flooding from wind surge from major storms such as Sandy, the “superstorm” that flooded New York City and wiped out huge chunks of the Jersey shore last year.

“It’s going to happen,” said Boesch, who led the commission’s Scientific and Technical Working Group. In addition to seas rising, land in Maryland has been sinking as a result of ancient geological events.

“Our estimate is we should prepare for a sea level that’s going to be almost up to my chest, well over my knees,” Boesch said. “We better prepare for that. We need to be ready to make some difficult and tough decisions about what we’re going to protect.”

The options are clear: Raise houses, place utility poles on high ground “so they’re not destroyed in every flood,” Boesch said.

Municipal planners facing similar issues in coastal regions nationwide have proposed another option: Retreat from areas that cannot be saved — do not locate schools, police stations, firehouses and other buildings meant to last 75 years in places projected to flood.

Homeowners in those areas should be given options: Leave the land with some compensation or stay at their own peril, according to an Environmental Protection Agency analysis called “Rolling Easements,” the latest manual instructing municipalities on ways to deal with rising tides.

Residents who hunker down should have the option of building expensive dikes and other easements at their own expense and paying higher rates of insurance. But they should not expect authorities to rescue them or relatives who assume ownership of threatened properties, and they should know that police and other emergency vehicles might one day be unable to plow through the waters to protect them.

Maryland is one of many governments worrying over rising sea levels and exploring ways to counter them.

University scientists have served on panels in New York, New Jersey, Virginia and Florida to research the topic. The National Research Council studied the impact of sea-level rise in Washington, Oregon and California.

On the Atlantic coast, Maryland’s effort to adapt is among the most advanced, said Robert E. Kopp, associate director of the Rutgers Energy Institute. “Maryland is a lot more aggressive than New Jersey has been, at least before Sandy” tore apart Atlantic City, he said. Broward and Dade counties in Florida have also launched scientific studies related to climate and the seas.

The threat of a rising tide that could lead to heavy flooding in Baltimore, Annapolis, St. Michaels and the lower half of the Delmarva Peninsula below Cambridge is among the topics to be discussed Thursday at the Maryland Climate Change Summit, led by Gov. Martin O’Malley (D) at the Conference Center at the Maritime Institute in Linthicum Heights. The summit will also cover efforts to develop more renewable energy projects.

O’Malley directed state agencies to consider the risk of coastal flooding and sea-level rise for capital investments in an executive order he signed in December. Under that order, the technical working group revisited the Maryland Climate Action Plan of 2008 and its projections of a sea-level rise of up to 3.4 feet under a scenario of higher greenhouse-gas emissions.

The group’s experts on climate change and sea-level rise paid close attention to more recent papers on the issue, including U.S. Geological Survey research published in the journal Nature Climate Change, which had higher projections.

That study said sea levels along the Atlantic Ocean from Cape Hatteras, N.C., to Boston, with Maryland almost in the middle, “have risen at an annual rate three times to four times faster than the global average.”

Using the latest research into ice melt and climate change by the National Research Council, the Intergovernmental Panel on Climate Change and other agencies, the group came to its projected sea-level rise for Maryland.

Some of the increase would result from a gradual sinking of land that has been occurring for centuries, but sea-level rise is expected to accelerate in the 21st century, making matters worse.

Low-lying and flat, the coastline of Maryland’s Eastern Shore will gradually recede, according to projections, and the waterfront of historic St. Michaels would be at risk if some structures are not raised, Boesch said.

Scientists did not have to use their imaginations to see what can happen. A few miles south of the peninsula in the Tidewater area, Norfolk and Virginia Beach are experiencing increased flooding. Norfolk is studying a plan to upgrade its sewer and drainage system for relief.

The Miami area’s crown jewel, South Beach, faces heavy flooding in rains and from ocean waters whipped by storm surge. City leaders are desperately seeking a fix. A barrier such as the gates built in New Orleans and proposed in New York would not be effective because water can seep through South Florida’s porous limestone.

Darryl Fears has worked at The Washington Post for more than a decade, mostly as a reporter on the National staff. He currently covers the environment, focusing on the Chesapeake Bay and issues affecting wildlife.

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